From 5101ab2d13e2b89ea3c1276df5fb7413634eeccd Mon Sep 17 00:00:00 2001
From: Mike Brady <mikebrady@eircom.net>
Date: Sat, 25 Aug 2018 13:08:37 +0100
Subject: [PATCH] Sometimes libsoxr is built to rely on libavutil. If libavutil
 is detected, link to it when building libsoxr. Add pgk_config support to soxr
 selection.
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The Buildroot autobuilder detected a build issue [0] when building
shairport-sync statically:

```
arm-buildroot-linux-uclibcgnueabi/sysroot/usr//lib/libsoxr.a(soxr.c.o): In function `soxr_create':
soxr.c:(.text+0xd4c): undefined reference to `av_get_cpu_flags'
collect2: error: ld returned 1 exit status
```

A quick look at the soxr source code shows that `soxr_create()` might use
`av_get_cpu_flags()` depending on the architecture.

For the sake of simplicity link with `-lavutil` if it is found when using soxr.

Even better, as soxr provides a pkg-config file, this should be prefered.

[0] http://autobuild.buildroot.org/results/53d/53d21686780aa2485745b59e812b6280dd39f1c5

Upstream status: 5101ab2d13e2b89ea3c1276df5fb7413634eeccd

Signed-off-by: Jörg Krause <joerg.krause@embedded.rocks>
---
 configure.ac | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/configure.ac b/configure.ac
index 0c917a4..2b6fddb 100644
--- a/configure.ac
+++ b/configure.ac
@@ -176,7 +176,20 @@ AC_ARG_WITH(ssl, [ choose --with-ssl=openssl, --with-ssl=mbedtls or --with-ssl=p
 # Look for soxr flag
 AC_ARG_WITH(soxr, [  --with-soxr = choose libsoxr for high-quality interpolation], [
   AC_MSG_RESULT(>>Including support for soxr-based interpolation)
-  AC_CHECK_LIB([soxr],[soxr_create], , AC_MSG_ERROR(soxr support requested but libsoxr not found!))], )
+  if  test "x${with_pkg_config}" = xyes ; then
+    PKG_CHECK_MODULES(
+        [SOXR], [soxr],
+        [LIBS="${SOXR_LIBS} ${LIBS}"])
+  else
+    AC_CHECK_LIB([avutil],[av_get_cpu_flags])
+    if  test "x${ac_cv_lib_avutil_av_get_cpu_flags}" = xyes ; then
+      # soxr may link against libavutil, depending on the architecture, but for the sake of simplicity link with it if it is found
+      AC_CHECK_LIB([soxr],[soxr_create], , AC_MSG_ERROR(soxr support requested but libsoxr not found!), [-lavutil])
+    else
+      AC_CHECK_LIB([soxr],[soxr_create], , AC_MSG_ERROR(soxr support requested but libsoxr not found!))
+    fi
+  fi
+], )
 
 # Look for metadata flag -- set flag for conditional compilation
 AC_ARG_WITH(metadata, [  --with-metadata = include support for a metadata feed], [
-- 
2.18.0
